There is a chance that former National Basketball Association (NBA) star Dennis Rodman’s surprise return to North Korea could help secure the release of an American being held in the repressive nation, but it also raises serious concerns, analysts say.

Wearing sunglasses, a dark shirt and baseball cap, and with facial piercings, Rodman told reporters on Tuesday that “I'm just trying to open the door," after he was spotted at the Beijing International Airport en route to Pyongyang.

In Tokyo, U.S. Under Secretary of State Thomas Shannon confirmed that Rodman was traveling to North Korea as a private citizen and said, "We wish him well. But we have issued travel warnings to Americans and suggested they not travel to North Korea for their own safety.”

The 56-year-old former basketball star has visited North Korea at least four times and developed a friendship with its young leader Kim Jong Un, who is an avid NBA fan, and in particular is a fan of the Michael Jordan-led championship Chicago Bulls team that Rodman was a part of in 1990s. Rodman has affectionately referred to the authoritarian leader as “the Marshall,” and has also called him an “awesome kid.” He has said in the past the purpose of his trips have been to help "open the door" to the reclusive state.

Useful pawn

Rodman’s return to North Korea, even as a private citizen, has immediately raised concerns that he will be used as a pawn to bolster a sympathetic image of the Kim regime.

“With Dennis Rodman’s celebrity I think it is bringing attention to Kim Jong Un that he does not deserve and shouldn’t get,” said Anthony Ruggiero, a North Korea analyst and Senior Fellow for the Foundation for Defense of Democracies in Washington.

Rodman’s unofficial diplomacy, Ruggiero said, could also undermine international efforts to increase sanctions on Pyongyang for its continued nuclear and ballistic missiles programs and for its ongoing human rights violations. Since 2016 North Korea has conducted dozens of missile launches and two nuclear bomb tests, and has indicated its goal is to develop a nuclear-tipped intercontinental ballistic missile capable of hitting the U.S. mainland.

U.S. Defense Secretary Jim Mattis said on Monday that North Korea's advancing missile and nuclear programs were the "most urgent" threat to national security.

Americans detained

Asked about U.S. citizens detained in North Korea, Rodman told reporters at Beijing's international airport that he thinks he can "make something happen."

Rodman may have played a key role in gaining the 2014 release of American missionary Kenneth Bae, who was charged with “hostile acts against the state,” and spent two years in a North Korean labor camp. A number of missionaries have been arrested by North Korea for violating a ban on proselytizing, which is considered a crime against the state.

During Rodman’s last trip in 2014, he played in an exhibition basketball game with NBA All-Stars and sang “happy birthday” to Kim, who was in attendance. But the NBA star was also reportedly inebriated much of that trip and got into a contentious argument during a CNN interview in which he implied the detainment of Bae was justified.

He later apologized for his comments and wrote to Kim Jong Un asking for Bae’s release. In his letter, Rodman called Kim his “friend for life,” noted that Bae had committed crimes, and asked for clemency to “show my country how loving and compassionate” the North Korean leader is.

In November of 2014, then-U.S. intelligence chief James Clapper visited Pyongyang and negotiated the release of Kenneth Bae and Matthew Miller, another American who was being held. But Bae has since credited Rodman for being the catalyst for his release.

North Korea travel ban

In the past, former presidents Bill Clinton and Jimmy Carter also came to North Korea to negotiate the release of Americans being detained.

Currently four Americans are being held in North Korea, including 22-year-old student Otto Warmbier, who was detained in January 2016 and sentenced to 15 years' hard labor for attempting to steal a propaganda banner.

While Ruggiero hopes for their release, he said the United States should ban all travel to North Korea to prevent the leadership in Pyongyang a means of leverage to influence public opinion or to extract concessions.

“It distracts from and it legitimizes North Korea’s weapons and missiles programs and that is Kim Jong Un’s goal. Why would we feed into that goal of his?” he asked.

Rodman also has a connection to U.S. President Donald Trump, having appeared twice on the "Celebrity Apprentice" television program that Trump hosted, and during last year's election campaign he praised the future president on Twitter.

Trump has at times indicated a willingness to negotiate with Kim Jong Un, saying he would be "honored" to meet him under the right conditions, and described the young leader as "a pretty smart cookie." But the president has also described the North Korean leaders as a "madman with nuclear weapons."